Devices fabricated using semiconductor-on-insulator (SOI) technologies may exhibit certain performance improvements in comparison with comparable devices built directly in a bulk silicon substrate. Generally, an SOI wafer includes a thin device layer of semiconductor material, a handle substrate, and a thin buried insulator layer, such as a buried oxide or BOX layer, physically separating and electrically isolating the device layer from the handle substrate. Integrated circuits are fabricated using the semiconductor material of the device layer.
Wafer thinning has been driven by the need to make packages thinner to accommodate stacking and high density packaging of chips. An SOI wafer may be thinned by removing the handle wafer from its construction. Once thinned, the backside surface of the SOI wafer may be subjected to additional operations. To lend mechanical support during thinning and the additional operations performed subsequent to thinning, the frontside surface bearing the integrated circuits may be adhesively bonded to a temporary substrate. After the additional operations are performed, a final substrate may be attached to the backside surface and the temporary substrate may be removed.
Improved device structures and fabrication methods are needed for a backside contact to a final substrate.